1. Field of the Invention:
The present invention is in the field of curable compositions and more particularly to curable coating compositions which are useful as clear coats in color-plus-clear coating applications. The invention also relates to a process for preparing color-plus-clear coated articles and to the coated articles themselves.
2. Brief Description of the Prior Art:
Color-plus-clear coatings involve the application of a colored or pigmented base coat to a substrate followed by the application of a transparent or clear top coat to the base coat. The composite coatings are becoming increasingly popular as original finishes for automobiles. The color-plus-clear coatings have outstanding gloss and distinctness of image, and the clear coat is particularly important for these properties. Two-pack clear coat compositions comprising polyols such as polyester polyols, polyurethane polyols and acrylic polyols and polyisocyanate curing agents give outstanding gloss and distinctness of image along with good humidity resistance and mar resistance. However, the polyisocyanates are difficult to handle being sensitive to moisture and require cumbersome safety precautions because of their toxicity.
U.S. Pat. No. 4,650,718 discloses crosslinkable coating compositions which avoid the problems of polyisocyanate curing agents. The crosslinkable coating compositions are based on polyepoxides and polyacid curing agents. Although these compositions can be formulated to produce cured coatings with excellent adhesion, gloss and distinctness of image (i.e., ability to reflect images in a clear, well-defined manner), the resultant cured coatings do not have optimum humidity and mar resistance.